1. Field of the Invention
This invention relates to a method for controlling a rotary memory device such as a magnetic disk memory for storing a record unit including an address section and a data section on a recording medium in the form of a track.
2. Description of the Prior Art
In a magnetic disk device such as used in a general purpose computor system, a fixed address for physically specifying a one-to-one correspondence, which is used in a main memory device, is not provided, but an address section (hereafter referred to as a count section) is provided for the identification of the information to be stored. Moreover, the length of a unit piece of information to be recorded (hereafter referred to simply as "the record") is variable and a specific flag called an address marker is attached to the head of a record so as to identify the beginning of the record.
The widely used method of writing an address marker at the top of a record is to erase a portion of the recording medium by a direct current. This method is different from that for the writing of information and therefore a special circuit should be provided for the writing of the address markers. Further, the identification of address markers also needs a circuit different from that required for the reading of information. Thus, these additional requirements lead to an increase in the complexity of the overall apparatus.
Moreover, since the identification of a record depends only upon the associated address marker, the hardware must be more complicated to assure the exact access to the beginning of information.